Large caliber guns have been found to be subjected to thermally induced deflections, particularly during repeated fire, and these deflections change the muzzle pointing angle. This in turn significantly affects the projectile impact location.
Efforts have been made to minimize impact errors. In order to do this, a muzzle reference sight has been proposed to be attached to the gun muzzle. This muzzle reference sight is intended to provide information to the gunner by quantifying changes in muzzle pointing angle. This information is provided as input into an existing fire control computer or may be used directly by the gunner to correct the aim point and/or realign the gun sights with the new muzzle pointing angle.
Most muzzle reference sights are either optical devices that emit a reference beam of light, or they are devices using mirrors which reflect a reference beam of light. This provides a response to changes which are thermally induced into the gun muzzle, so that initially parallel sighting between the gunners sight and the muzzle reference sight is corrected by adjustment of the gunners sight to conform to changes detected by the muzzle reference sight.
It has been discovered that the mounting technique which is used to secure the muzzle reference sight to the gun tube is a critical link. The prior art has failed to appreciate that if the muzzle reference sight mount moves with respect to the muzzle, the entire system can be degraded or may even produce errors greater than the system has been designed to correct.
Prior art methods of mounting a muzzle reference sight system may be classified into two basic groups. Prior art systems involve either a strap on device or a bolt on device. Strap on devices are typically composed of steel bands which are tightened on the gun tube with bolts. Because the tension is applied at one location, the straps must be flexible enough to equally distribute the tension and yet must also be strong enough to resist deformation during firing.
No such combination has been achieved for guns such as 120 mm high energy canons. Prior art designs which minimally function for 105 mm canons have failed when tested on the next generation models, such as 120 mm canons. Even with significant effort being made to strengthen the prior art strap device, no satisfactory design has been achieved.
Bolt on designs which include flat platforms have been proposed as well. These designs also have inherent problems which limit their effectiveness. As pressure in the gun tube causes the tube to dilate, either the platform must warp or the tube must deform asymmetrically. Warping of the platform can and often does break the mounting bolts or warp the muzzle reference sight. ,Asymmetric deformation of the gun tube will degrade accuracy and decrease tube life. Both problems are not possible to be avoided.
The problem with muzzle reference sights is seen as getting more severe as current developments produce much higher muzzle forces Even on current experimental guns and even using current ammunition, the prior art systems have failed. Extremely high forces have broken the muzzle reference sight systems. Development of more powerful ammunition will achieve improved performance, but will produce even greater muzzle forces, thus making prior art muzzle reference sight systems even less effective. Application of future ammunition to improved guns will degrade present systems, possibly to a point of uselessness
Accordingly, it is an object of the present invention to develop an improved muzzle reference sight system. More particularly, it is an object of this invention to develop a muzzle reference sight which avoids slippage, and which is somehow isolated from severe muzzle loads. Other objects will appear hereinafter.